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1.
J Sci Food Agric ; 102(7): 2960-2971, 2022 May.
Artículo en Inglés | MEDLINE | ID: mdl-34766350

RESUMEN

BACKGROUND: Blood oranges are grown increasingly in Europe for fresh consumption because of their special taste and excellent nutraceutical properties that confer the status of a functional food. The health benefits are associated with the range of additional bioactive compounds that they contain with respect to blonde oranges. RESULTS: We analysed the physicochemical properties and the levels of organic acids, sugars and antioxidants in 11 blood orange cultivars representing the most representative cultivars of blood oranges widespread in the Mediterranean basin. In particular, we examined the levels of phenols, flavonoids and anthocyanins present in these cultivars at harvest maturity. The physicochemical, antioxidant and colour properties differ significantly among these cultivars. The deepest red peel and juice was found in Sanguinelli, followed by Tarocco Rosso and Moro. High-performance liquid chromatography with refractive index detector analysis revealed sucrose as the main sugar in all these cultivars, followed by fructose and glucose. Citric acid was the dominant organic acid, followed by malic acid and ascorbic acid. Moro showed the greatest levels of antioxidant activity. Regarding the phenolic composition, we found p-coumaric acid to be the main hydroxycinnamic acid in all cultivars, with maximum amounts in Moro and Sanguinelli. The highest amounts of cyanidin-3-O-glucoside and cyanidin-3-(6''-malonyl)-glucoside were found in Moro, for which the juice was of the deepest red colour. CONCLUSION: The phenolic composition and antioxidant activity of the 11 cultivars was assessed. The results showed that Moro was the cultivar with the highest content of polyphenols and levels of antioxidant activity, followed by Sanguinelli. © 2021 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.


Asunto(s)
Antocianinas , Citrus sinensis , Antocianinas/análisis , Antioxidantes/química , Citrus sinensis/química , Frutas/química , Glucósidos/análisis , Fenoles/análisis , Azúcares/análisis
2.
Rep Pract Oncol Radiother ; 21(2): 113-6, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-26933393

RESUMEN

AIM: The main purpose of this work is to present a new (n,α) cross-section measurement for a stable isotope of sulfur, (33)S, in order to solve existing discrepancies. BACKGROUND: (33)S has been studied as a cooperating target for Boron Neutron Capture Therapy (BNCT) because of its large (n,α) cross-section in the epithermal neutron energy range, the most suitable one for BNCT. Although the most important evaluated databases, such as ENDF, do not show any resonances in the cross-section, experimental measurements which provided data from 10 keV to 1 MeV showed that the lowest-lying and strongest resonance of (33)S(n,α) cross-section occurs at 13.5 keV. Nevertheless, the set of resonance parameters that describe such resonance shows important discrepancies (more than a factor of 2) between them. MATERIALS AND METHODS: A new measurement of the (33)S(n,α)(30)Si reaction cross-section was proposed to the ISOLDE and Neutron Time-of-Flight Experiments Committee of CERN. It was performed at n_TOF(CERN) in 2012 using MicroMegas detectors. RESULTS: In this work, we will present a brief overview of the experiment as well as preliminary results of the data analysis in the neutron energy range from thermal to 100 keV. These results will be taken into account to calculate the kerma-fluence factors corresponding to (33)S in addition to (10)B and those of a standard four-component ICRU tissue. CONCLUSIONS: MCNP simulations of the deposited dose, including our experimental data, shows an important kerma rate enhancement at the surface of the tissue, mainly due to the presence of (33)S.

3.
Eur J Clin Invest ; 45(12): 1325-32, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26509357

RESUMEN

BACKGROUND: Currently, there are no predictive biomarkers for anti-angiogenic strategies in cancer, but response to anti-angiogenic drugs is associated with development of hypertension secondary to treatment. Therefore, this study explored the clinical relevance of genetic polymorphisms in some components of the renin-angiotensin system (RAS). MATERIAL AND METHODS: Genomic DNA was isolated from peripheral blood from 95 metastatic breast or colorectal cancer patients treated with bevacizumab, and AGTR1-A1166C (rs5186), AGT-M235T (rs699) SNPs and ACE I/D (rs4646994) polymorphisms were genotyped using RT-PCR. Circulating vascular endothelial grow factor and angiotensin converting enzyme (ACE) levels were analysed using ELISA kits. The antitumoral activity of bevacizumab was assayed in mice orthotopically xenografted with AGTR1-overexpressing breast cancer cells. RESULTS: The ACE IN/IN genotype was associated with a higher rate of disease progression compared to DEL/IN and DEL/DEL genotypes (36% vs. 11·1% P < 0·05). Similarly, AGTR1-1166A/A genotype was also associated with a higher rate of disease progression compared to AGTR1-1166A/C and AGTR1-1166C/C genotypes (24·4% vs. 2·7% P < 0·01). ACE IN/IN genotype was also found to be associated with shorter time to treatment failure compared to ACE IN/DEL and ACE DEL/DEL genotypes (14 weeks vs. 41·71, P = 0·033), whereas circulating ACE levels were found to be associated with a better response to bevacizumab treatment. Besides, in vivo experiments showed a significantly higher antitumoral activity of bevacizumab in tumours derived from AGTR1-overexpressing breast cancer cells. CONCLUSIONS: A higher activity of ACE-angiotensin-II-AGTR1 axis is associated with a better response to bevacizumab, supporting that the RAS can be an important source of potential predictive markers of response to anti-angiogenic drugs.


Asunto(s)
Inhibidores de la Angiogénesis/uso terapéutico , Bevacizumab/uso terapéutico , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias Colorrectales/tratamiento farmacológico , Sistema Renina-Angiotensina/genética , Adulto , Anciano , Anciano de 80 o más Años , Angiotensina II/metabolismo , Animales , Neoplasias de la Mama/genética , Neoplasias Colorrectales/genética , Ensayo de Inmunoadsorción Enzimática , Femenino , Genotipo , Xenoinjertos/metabolismo , Humanos , Masculino , Ratones Endogámicos NOD , Ratones SCID , Persona de Mediana Edad , Metástasis de la Neoplasia , Trasplante de Neoplasias , Peptidil-Dipeptidasa A/metabolismo , Polimorfismo Genético , Estudios Prospectivos , Receptor de Angiotensina Tipo 1/genética , Estudios Retrospectivos , Factor A de Crecimiento Endotelial Vascular/metabolismo
4.
Front Pharmacol ; 15: 1352939, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38469410

RESUMEN

Background: Chemotherapy-induced peripheral neuropathy (CIPN) is a common entity (30%-40%) and can significantly limit the quality of life of patients, especially those that persist for more than 6 months after treatment (chronic neuropathy). Studies have shown a possible association between the presence of genetic polymorphisms in ABCB1 and the development of acute CIPN, although this relationship with chronic CIPN remains unexplored. This is an analytical observational case-control study defined by the presence (cases) or absence (controls) of CIPN at 6 months after the end of the neurotoxic drug. Our aim is to demonstrate whether these ABCB1 polymorphisms also influence the chronification of this toxicity, as well as the clinical factors that can help us to predict it. Methods: The study included 152 patients treated with tri-weekly oxaliplatin (O) or weekly paclitaxel (P); 86 cases and 66 controls. Clinical and analytical parameters were analysed including the study of ABCB1 genetic polymorphisms in a blood sample. Results: ABCB1 genetic polymorphisms C1236T (rs1128503) and C3435T (rs1045642) are associated with the development of chronic CIPN in patients treated with P. No differences were found in patients treated with O. Other predictive factors to be considered in the development of this toxicity are age >60 years, BMI ≥30, toxic habits and cardiovascular risk factors. Conclusion: CIPN is a common and understudied toxicity, despite being a limiting factor in the quality of life of many patients. As described in acute CIPN, our study demonstrates the relationship between chronic neuropathy and being a carrier of specific polymorphisms (C1236T and C3435T) of the ABCB1 gene in patients treated with P. In addition, there are modifiable factors (obesity, smoking, or alcohol) that may influence its development. Further prospective studies are needed to investigate genetic and clinical modifiable factors predisposing to CIPPN to develop prevention and treatment strategies.

5.
Rep Pract Oncol Radiother ; 21(2): 93-4, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-26933389
6.
Biology (Basel) ; 10(5)2021 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-33925863

RESUMEN

Boron Neutron Capture Therapy (BNCT) is a binary radiation treatment exploiting a nuclear reaction occurring in tumor cells [...].

7.
Sci Rep ; 11(1): 7576, 2021 04 07.
Artículo en Inglés | MEDLINE | ID: mdl-33828211

RESUMEN

Boron Neutron Capture Therapy (BNCT) is facing a new era where different projects based on accelerators instead of reactors are under development. The new facilities can be placed at hospitals and will increase the number of clinical trials. The therapeutic effect of BNCT can be improved if a optimized epithermal neutron spectrum is obtained, for which the beam shape assembly is a key ingredient. In this paper we propose an optimal beam shaping assembly suited for an affordable low energy accelerator. The beam obtained with the device proposed accomplishes all the IAEA recommendations for proton energies between 2.0 and 2.1 MeV. In addition, there is an overall improvement of the figures of merit with respect to BNCT facilities and previous proposals of new accelerator-based facilities.


Asunto(s)
Terapia por Captura de Neutrón de Boro/instrumentación , Neutrones , Aceleradores de Partículas/instrumentación , Protones , Terapia por Captura de Neutrón de Boro/estadística & datos numéricos , Simulación por Computador , Diseño de Equipo , Humanos , Aceleradores de Partículas/estadística & datos numéricos , Fantasmas de Imagen , Dosificación Radioterapéutica
8.
Appl Radiat Isot ; 157: 109018, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31889683

RESUMEN

The current methodology for determining the biological effect of Boron Neutron Capture Therapy (BNCT) has recently been questioned, and a more accurate framework based in the photon iso-effective dose has been proposed. In this work we derive a first order approximation to this quantity. The new approach removes the main drawbacks of the current method, being based on new weighting factors which are true constants (dose independent) but which can be evaluated from published data on the existing (dose-dependent) weighting factors. In addition to this, we apply the formalism to allow the comparison to a fractionated conventional radiotherapy treatment, for which there is a lot of knowledge from clinical practice. As an application, the photon iso-effective dose of a BNCT treatment for a brain tumor is estimated. An excel sheet used for these calculations is also provided as supplementary material and can be used also with user-provided input data for the estimation of the photon iso-effective dose for comparison with conventional radiotherapy, both to single and fractionated treatments.


Asunto(s)
Terapia por Captura de Neutrón de Boro/métodos , Dosificación Radioterapéutica , Animales , Neoplasias Encefálicas/radioterapia , Relación Dosis-Respuesta en la Radiación , Gliosarcoma/radioterapia , Humanos , Fotones/uso terapéutico , Ratas
9.
Appl Radiat Isot ; 163: 109205, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-32392166

RESUMEN

The cold neutron beam at the PF1b line at the Institut Laue-Langevin (ILL), without fast neutrons and a low contribution of gamma rays, is a very suitable facility to measure cell damage following low-energy neutron irradiation. The biological damage associated with the thermal and the boron doses can be obtained in order to evaluate the relative biological effectiveness (RBE) for Boron Neutron Capture Therapy. Three different experiments were carried out on the A375 melanoma cell line: the first one in a hospital LINAC, to obtain the reference radiation data, and the other two at the ILL, in which the damage to cells with and without boron compounds added was measured.


Asunto(s)
Compuestos de Boro/administración & dosificación , Melanoma/patología , Terapia por Captura de Neutrón de Boro/métodos , Línea Celular Tumoral , Humanos , Neutrones
10.
Cells ; 9(10)2020 09 23.
Artículo en Inglés | MEDLINE | ID: mdl-32977400

RESUMEN

The experimental determination of the relative biological effectiveness of thermal neutron factors is fundamental in Boron Neutron Capture Therapy. The present values have been obtained while using mixed beams that consist of both neutrons and photons of various energies. A common weighting factor has been used for both thermal and fast neutron doses, although such an approach has been questioned. At the nuclear reactor of the Institut Laue-Langevin a pure low-energy neutron beam has been used to determine thermal neutron relative biological effectiveness factors. Different cancer cell lines, which correspond to glioblastoma, melanoma, and head and neck squamous cell carcinoma, and non-tumor cell lines (lung fibroblast and embryonic kidney), have been irradiated while using an experimental arrangement designed to minimize neutron-induced secondary gamma radiation. Additionally, the cells were irradiated with photons at a medical linear accelerator, providing reference data for comparison with that from neutron irradiation. The survival and proliferation were studied after irradiation, yielding the Relative Biological Effectiveness that corresponds to the damage of thermal neutrons for the different tissue types.


Asunto(s)
Terapia por Captura de Neutrón de Boro , Neoplasias/tratamiento farmacológico , Neutrones/uso terapéutico , Efectividad Biológica Relativa , Terapia por Captura de Neutrón de Boro/métodos , Rayos gamma , Humanos
11.
Clin Genitourin Cancer ; 16(6): e1133-e1139, 2018 12.
Artículo en Inglés | MEDLINE | ID: mdl-30104161

RESUMEN

INTRODUCTION: Although increasing numbers of therapies with proven survival benefits have become available for metastatic castration-resistant prostate cancer (mCRPC), including radium-223, there is still a need for reliable biomarkers that provide information about clinically meaningful outcomes and treatment responses. MATERIALS AND METHODS: This study was a translational study that was conducted prospectively by the Spanish Oncology Genito-Urinary Group and included 45 patients with histologically confirmed mCRPC who were treated with radium-223. The primary response outcome was defined by a decline in circulating tumor cells (CTCs) of > 50% from baseline or a CTC count of ≤ 5 cells/7.5 mL at cycle 3 of radium-223. We also assessed response according to prostate-specific antigen and alkaline phosphatase levels. CTCs were evaluated as prognostic factor for treatment completion with radium-223 treatment. Kaplan-Meier estimates of survival were calculated for the global population and were correlated with biomarker response outcomes. RESULTS: Significantly, more patients with baseline CTC counts ≤ 5/7.5 mL, which are indicative of better prognoses, completed the 6 injections of therapy than those with CTC counts > 5 (16/22; 73% vs. 6/20; 30%, respectively; P = .012). The median overall survival was 16 months. Survival was significantly decreased in patients with baseline CTC counts > 5 cells/7.5 mL (7 months; P = .026) and baseline alkaline phosphatase levels ≥ 220 U/L (8 months; P = .028). CONCLUSIONS: CTCs hold significant promise as a prognostic factor for survival and completing treatment prior to the initiation of bone-targeted radium-223 therapy. These findings may help to guide the use of radium-223 in patients with mCRPC.


Asunto(s)
Neoplasias Óseas/radioterapia , Células Neoplásicas Circulantes/efectos de la radiación , Neoplasias de la Próstata Resistentes a la Castración/radioterapia , Radio (Elemento)/administración & dosificación , Anciano , Anciano de 80 o más Años , Neoplasias Óseas/sangre , Neoplasias Óseas/mortalidad , Neoplasias Óseas/secundario , Recuento de Células , Progresión de la Enfermedad , Estudios de Seguimiento , Humanos , Inyecciones Intravenosas , Masculino , Pronóstico , Supervivencia sin Progresión , Estudios Prospectivos , Antígeno Prostático Específico/sangre , Neoplasias de la Próstata Resistentes a la Castración/sangre , Neoplasias de la Próstata Resistentes a la Castración/mortalidad , Neoplasias de la Próstata Resistentes a la Castración/patología , Dosificación Radioterapéutica
12.
Eur J Endocrinol ; 177(4): 309-317, 2017 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-28687563

RESUMEN

BACKGROUND: Axitinib, an antiangiogenic multikinase inhibitor (MKI), was evaluated in the compassionate use programme (CUP) in Spain (October 2012-November 2014). SUBJECTS AND METHODS: 47 patients with advanced radioactive iodine (RAI)-refractory differentiated thyroid cancer (DTC, n = 34) or medullary thyroid cancer (MTC, n = 13) with documented disease progression were treated with axitinib 5 mg b.i.d. The primary efficacy endpoint was objective response rate (ORR) by Response Evaluation Criteria In Solid Tumors (RECIST) v1.1. Progression-free survival (PFS) and adverse events (AEs) were secondary objectives. Regulatory authorities validated the CUP, and all patients signed informed consent form. RESULTS: Axitinib was administered as first-line therapy in 17 patients (36.2%), as second-line in 18 patients (38.3%) and as third/fourth-line in 12 patients (25.5%). With a median follow-up of 11.5 months (0-24.3), ORR was 27.7% (DTC: 29.4% and MTC: 23.1%) and median PFS was 8.1 months (95% CI: 4.1-12.2) (DTC: 7.4 months (95% CI: 3.1-11.8) and MTC: 9.4 months (95% CI: 4.8-13.9)). Better outcomes were reported with first-line axitinib, with an ORR of 53% and a median PFS of 13.6 months compared with 16.7% and 10.6 months as second-line treatment. Twelve (25.5%) patients required dose reduction to 3 mg b.i.d. All-grade AEs included asthenia (53.2%), diarrhoea (36.2%), hypertension (31.9%) and mucositis (29.8%); grade 3/4 AEs included anorexia (6.4%), diarrhoea (4.3%) and cardiac toxicity (4.3%). CONCLUSION: Axitinib had a tolerable safety profile and clinically meaningful activity in refractory and progressive thyroid cancer regardless of histology as first-line therapy. To our knowledge, this is the first time that cross-resistance between MKIs is suggested in thyroid cancer, highlighting the importance of prospective sequential clinical studies.


Asunto(s)
Imidazoles/uso terapéutico , Indazoles/uso terapéutico , Radioisótopos de Yodo , Inhibidores de Proteínas Quinasas/uso terapéutico , Neoplasias de la Tiroides/diagnóstico por imagen , Neoplasias de la Tiroides/tratamiento farmacológico , Adulto , Anciano , Anciano de 80 o más Años , Axitinib , Carcinoma Neuroendocrino/diagnóstico por imagen , Carcinoma Neuroendocrino/tratamiento farmacológico , Carcinoma Neuroendocrino/epidemiología , Femenino , Humanos , Estudios Longitudinales , Imagen por Resonancia Magnética/métodos , Masculino , Persona de Mediana Edad , Tomografía Computarizada por Tomografía de Emisión de Positrones/métodos , Estudios Retrospectivos , España/epidemiología , Neoplasias de la Tiroides/epidemiología , Resultado del Tratamiento
13.
Rev. urug. cardiol ; 35(3): 322-361, dic. 2020. tab, graf
Artículo en Español | LILACS-Express | LILACS | ID: biblio-1145088

RESUMEN

Resumen: Todos los pacientes que cursan un posoperatorio de cirugía cardíaca desarrollan alteraciones respiratorias. Por esta razón, es muy importante la implementación de todas las medidas tendientes a minimizar el impacto de estas. El verdadero desafío consiste en la detección precoz de dichas complicaciones y el desarrollo de estrategias terapéuticas tempranas con el objetivo de minimizar su impacto. En el presente trabajo, se analizan las principales complicaciones respiratorias en el escenario del posoperatorio de cirugía cardíaca y las acciones terapéuticas correspondientes.


Summary: All patients who undergo cardiac surgery develop respiratory disorders in the postoperative period. It is very important to implement all measures to minimize the impact of these alterations. The real challenge consists in the early detection of complications and the development of early therapeutic strategies in order to minimize their impact. In the present study, the main respiratory complications in the postoperative setting of cardiac surgery, and the corresponding therapeutic actions, are analyzed.


Resumo: Todos os pacientes submetidos à cirurgia cardíaca desenvolvem distúrbios respiratórios no pós-operatório. É muito importante implementar todas as medidas para minimizar o impacto dessas alterações. O verdadeiro desafio consiste na detecção precoce das complicações e no desenvolvimento de estratégias terapêuticas precoces de forma a minimizar o seu impacto. No presente trabalho, são analisadas as principais complicações respiratórias no pós-operatório de cirurgia cardíaca e as respectivas ações terapêuticas.

14.
Clin Breast Cancer ; 3 Suppl 1: 39-44, 2002 May.
Artículo en Inglés | MEDLINE | ID: mdl-12057045

RESUMEN

Neoadjuvant chemotherapy has become a standard treatment in the management of locally advanced breast cancer. Patients with earlier-stage disease may also benefit from neoadjuvant treatment in terms of improved rates of breast-conserving surgery and thus better quality of life. Gemcitabine is a pyrimidine analogue that has shown activity in a variety of solid tumors, a good toxicity profile, and nonoverlapping toxicity with other chemotherapeutic agents. Several phase II/III studies are assessing gemcitabine combined with anthracyclines, taxanes, and/or vinorelbine both in the neoadjuvant and metastatic disease settings. This article reviews developments in neoadjuvant use of gemcitabine in combination with anthracyclines and taxanes. Several phase II trials of gemcitabine combined with doxorubicin/epirubicin or with doxorubicin/paclitaxel have been carried out. Preliminary findings demonstrate increased complete response rates and good tolerability of these regimens in patients with breast cancer.


Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias de la Mama/tratamiento farmacológico , Desoxicitidina/análogos & derivados , Neoplasias de la Mama/patología , Ensayos Clínicos Fase II como Asunto , Desoxicitidina/administración & dosificación , Doxorrubicina/administración & dosificación , Epirrubicina/administración & dosificación , Femenino , Humanos , Terapia Neoadyuvante , Metástasis de la Neoplasia , Recurrencia Local de Neoplasia , Paclitaxel/administración & dosificación , Resultado del Tratamiento , Gemcitabina
15.
J Agric Food Chem ; 52(2): 324-31, 2004 Jan 28.
Artículo en Inglés | MEDLINE | ID: mdl-14733516

RESUMEN

The grafting of the rootstock with the lemon tree is an agronomical technique used to improve production and/or quality of the fruit. The interstock has been used with different fruit trees to modulate the tree size, fruit production and quality, and the aging of the tree. The lemon trees grafted with interstocks increase their longevity, lemon production and quality; interstocks are also used to decrease the thickness of the trunk at the grafting point. This enlarging of the trunk provokes a decrease of the sap flow. In our study, "Verna" lemon trees were grafted with interstock between the rootstock and the lemon tree to follow the flavonoid content of the lemon juice. The lemon juice was obtained from the lemons collected of the grafted lemon trees. Two types of rootstocks were used: Citrus aurantium L. and Citrus macrophylla L. Seven interstocks from five cultivars of orange tree, one cultivar of lime tree, and one cultivar of tangerine tree were used. "Verna" lemon trees were also grafted directly to the rootstock. The rootstock was more important agronomic factor than the interstock on the total flavonoid content of lemon juice. The interstock grafting had only a small influence on the flavonoid content of the lemon juice, and it modulated the individual flavonoid content. Citrus aurantium L. rootstock and "Berna" and "Washington Navel" interstocks were the most appropriate to graft in the lemon tree. This interstock grafting technique does not increase the flavonoid content of the lemon juice. Regarding the individual flavonoids, the 6,8-di-C-glucosyl diosmetin was the most affected flavonoid by the type of rootstock used. The interstock used is able to alter the individual quantitative flavonoid order of eriocitrin, diosmin, and hesperidin. In addition, the HPLC-ESI/MS(n) analyses provided the identification of two new flavonoids in the lemon juice: Quercetin 3-O-rutinoside-7-O-glucoside and chrysoeriol 6,8-di-C-glucoside (stellarin-2). The occurrence of apigenin 6,8-di-C-glucoside (vicenin-2), eriodictyol 7-O-rutinoside, 6,8-di-C-glucosyl diosmetin, hesperetin 7-O-rutinoside, homoeriodictyol 7-O-rutinoside and diosmetin 7-O-rutinoside was also confirmed in lemon juice by this technique.


Asunto(s)
Agricultura/métodos , Citrus/química , Citrus/crecimiento & desarrollo , Flavonoides/análisis , Frutas/química , Raíces de Plantas/fisiología , Cromatografía Líquida de Alta Presión , Soluciones , Espectrometría de Masa por Ionización de Electrospray
16.
Brachytherapy ; 13(4): 424-9, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-24561104

RESUMEN

PURPOSE: To investigate the peak shown by the American Association of Physicists in Medicine (AAPM) Task Group 43 1D anisotropy function at short distances from the source. METHODS AND MATERIALS: The 1D anisotropy function of an ideal nonencapsulated photon linear source is calculated. A simple analytical model developed to evaluate the dose because of photon point-like sources has been applied. Previously, the model has been tested by comparing the values obtained for the various Task Group 43 dosimetric functions with those calculated with the Monte Carlo code PENELOPE for three different photon energies. RESULTS: The model is able to reproduce the behavior of the 1D anisotropy function, describing the maximum that appears at a distance between 1 and 2 mm from the source. The reason for this behavior has been identified in terms of the contributions of the source activity inside and outside the scoring sphere. CONCLUSIONS: Although it is not usually shown in reference data, this behavior should be taken into account for accurate dosimetric calculations.


Asunto(s)
Braquiterapia/métodos , Radiometría/métodos , Anisotropía , Humanos , Modelos Estadísticos , Modelos Teóricos , Método de Montecarlo , Fotones , Dosificación Radioterapéutica
17.
Phys Med ; 29(4): 403-11, 2013 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-22698855

RESUMEN

A variation of TG-43 protocol for seeds with cylindrical symmetry aiming at a better description of the radial and anisotropy functions is proposed. The TG-43 two dimensional formalism is modified by introducing a new anisotropy function. Also new fitting functions that permit a more robust description of the radial and anisotropy functions than usual polynomials are studied. The relationship between the new anisotropy function and the anisotropy factor included in the one-dimensional TG-43 formalism is analyzed. The new formalism is tested for the (125)I Nucletron selectSeed brachytherapy source, using Monte Carlo simulations performed with PENELOPE. The goodness of the new parameterizations is discussed. The results obtained indicate that precise fits can be achieved, with a better description than that provided by previous parameterizations. Special care has been taken in the description and fitting of the anisotropy factor near the source. The modified formalism shows advantages with respect to the usual one in the description of the anisotropy functions. The new parameterizations obtained can be easily implemented in the clinical planning calculation systems, provided that the ratio between geometry factors is also modified according to the new dose rate expression.


Asunto(s)
Braquiterapia/métodos , Método de Montecarlo , Radiometría/métodos , Anisotropía , Dosificación Radioterapéutica
18.
J Plant Physiol ; 166(17): 1923-33, 2009 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-19604601

RESUMEN

Salinity is one of the major abiotic stresses affecting arable crops worldwide, and is the most stringent factor limiting plant distribution and productivity. In the present study, the possible use of in vitro culture to evaluate the growth and physiological responses to salt-induced stress in cultivated explants of Citrus macrophylla was analyzed. For this purpose, micropropagated adult explants were grown in proliferation and rooting media supplemented with different concentrations of NaCl. All growth parameters were decreased significantly by these NaCl treatments; this was accompanied by visible symptoms of salt injury in the proliferated shoots from 60mM NaCl and in the rooted shoots from 40mM NaCl. Malondialdehyde (MDA) increased with increasing salinity in proliferated shoots, indicating a rising degree of membrane damage. The concentration of total chlorophyll significantly decreased in the presence of NaCl, and this effect was more pronounced in the rooted explants. The Na(+) and Cl(-) concentrations in the explants increased significantly with the salinity level, but Cl(-) levels were higher in the proliferated explants than in the rooted explants. For osmotic adjustment, high concentrations of compatible solutes (proline and quaternary ammonium compounds-QAC) accumulated in salt-stressed plants in proliferation, but differences were not observed in rooted explants. In proliferation, proline and QAC were highly correlated with the sodium and chloride concentrations in the explants, indicating a possible role of these compounds in osmotic adjustment. The plant concentrations of NO(3)(-), K(+), Mg(2+), Ca(+) and Fe were also affected by the NaCl concentration of the medium. We suggest that the important deleterious effects in the in vitro explants of Citrus macrophylla grown at increasing NaCl concentrations were due mainly to toxic effects of saline ions, particularly Cl(-), at the cellular level.


Asunto(s)
Citrus/fisiología , Cloruro de Sodio/farmacología , Estrés Fisiológico , Clorofila/metabolismo , Citrus/efectos de los fármacos , Citrus/crecimiento & desarrollo , Malondialdehído/metabolismo , Presión Osmótica , Prolina/metabolismo , Compuestos de Amonio Cuaternario/metabolismo
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